Mr David Trimble returns to Belfast this morning at the start of a momentous 24 hours, which could determine the future of the Belfast Agreement and his leadership of Ulster Unionism.
Having failed to win any concessions from the British government on its decommissioning legislation in the Commons last night, Mr Trimble will hold separate meetings with his Assembly and parliamentary parties, ahead of tonight's meeting of his policymaking executive committee.
That will take him to within hours of the final "moment of truth" decision: whether to trigger the d'Hondt process for the appointment of ministers to the North's executive.
Mr Trimble has not yet ruled out any option. And while some members clearly hope to close his options at tonight's executive meeting, there were indications that he might postpone a final decision until tomorrow. At the same time there was strong speculation among sources close to Mr Trimble that any attempt to "force his hand" on d'Hondt without some dramatic eleventh-hour development could actually see him resign as First Minister-designate.
The sources suggested this would be the outcome should Mr Trimble decide he could not proceed to nominate ministers tomorrow, and if the British and Irish governments refused then to accede to his request to proceed straight to a "review" of the agreement.
With hopes for an IRA statement committed to decommissioning apparently fading, the impression at Westminster was that review is now Mr Trimble's preferred option, and resignation his least.
A third possible course whereby Mr Trimble would trigger d'Hondt "under protest", while tendering a post-dated resignation to take effect should decommissioning fail to start within a specified timetable, was still attracting interest in some unionist circles last night. But the sources told The Irish Times Mr Trimble would not take any action which would result in a further party split.
Contrary to earlier impressions, it emerged that a decision to go for a review prior to the triggering of the d'Hondt procedure would not necessarily involve a suspension of the Assembly. The new provision for suspension of the Assembly and executive in the case of "default" over devolution would only take effect after the appointment of the executive tomorrow, and the passage of the Devolution Order at Westminster scheduled for Friday.
After eight hours of impassioned debate in the House of Commons last night, the emergency Bill, including the controversial failsafe mechanism, was passed by 343 votes to 24.
Mr Trimble abstained in the vote but five Ulster Unionist MPs voted against the government, as did the Democratic Unionist leader Dr Ian Paisley, his deputy Mr Peter Robinson, the UK Unionist Mr Robert McCartney and 16 Tory MPs.
Earlier, a lacklustre parliamentary occasion followed signals from the government that it would defeat all proposed amendments to the Bill. However, official sources said later the government would "reflect" overnight on a number of issues raised during a powerful intervention by the former prime minister, Mr John Major.
Mr Major appealed to the SDLP to "commit themselves to staying in the Assembly and executive" should Sinn Fein be expelled because the IRA defaulted over decommissioning. He also pressed the government to include Gen de Chastelain's timetable for decommissioning in the Bill; and to amend it to provide that failure to comply with the general's requirements would be deemed a breach of the terms for ongoing prisoner releases.
In a bitter attack on the government, Mr Trimble said the Bill was "about taking an active and existing terrorist organisation into government" and saw "the democrats treated as if they were indistinguishable from the terrorists".
Referring to Mr Blair's admission that he could not force other parties to sit in government, Mr Trimble told the House this "means the SDLP don't want to sit with us if it means being apart from Sinn Fein".
Mr Seamus Mallon appealed to the UUP: "I'm not recommending trust. For the first time we have a way of establishing if decommissioning is going to happen. It never happened before. If does happen it will be seismic."